Array.prototype.myUnshift = function (...arr) {
  let len1 = this.length;
  let len2 = arr.length;
  for (let i = len1 - 1; i >= 0; i--) {
    this[i + len2] = this[i];
  }
  for (let i = 0; i < len2; i++) {
    this[i] = arr[i];
  }
};

Array.prototype.myUnshift = function (...args) {
  this.splice(0, 0, ...args);
};
